SUPERCONDUCTING OPEN-CONFIGURATION MR-IMAGING SYSTEM FOR IMAGE-GUIDEDTHERAPY

PURPOSE: To develop a superconducting magnetic resonance (MR) imager t hat provides direct access to the patient and permits interactive MR-g uided interventional procedures. MATERIALS AND METHODS: A 0.5-T superc onducting magnet that allows a region of vertical access to the patien t was designed and constructed. This magnet was integrated with newly designed shielded gradient coils, flexible surface coils, and nonmagne tic displays and with position-monitoring probes and device-tracking i nstrumentation. RESULTS: The magnet homogeneity was 12.3 ppm, and the gradient field was linear to within 1% over an imaging region 30 cm in diameter. The signal-to-noise ratio was 10% higher than in a comparab le 0.5-T superconducting imager. Images were obtained in several anato mic regions with use of routine pulse sequences. Interactive image pla ne selection and near real-time imaging, with use of fast gradient-rec alled echo sequences, were demonstrated at a rate of one image every 1 .5 seconds. CONCLUSION: MR-guided interventional procedures can be per formed with full patient access with use of an open-configuration, sup erconducting MR magnet with near real-time imaging and interactive ima ge plane control.